How to configure GnuPG's S.gpg-agent socket location?

Question

GnuPG places its socket S.gpg-agent at ~/.gnupg/S.gpg-agent by default. I didn't find any way to configure the location of this socket nor seems there to be a manpage of gpg.conf.

Background: I want to symlink ~/.gnupg to an OpenAFS mount which doesn't support sockets (and avoid to create a symlink for every file in ~/.gnupg (which is a workaround) instead of just ~/.gnupg), i.e. find the most elegant solution imo.

Answer 1

Since GnuPG Version 2.1.1 there exists a solution: Place a simple text-file S.gpg-agent in the gpg-homedir with following content:

%Assuan%
socket=/path/to/where/ever/you/want/S.gpg-agent

It replaces some evnvars like ${HOME} or ${HOSTNAME}

Be careful, when using a subdirectory of /tmp, because gpg-agent will not create needed directories.

Further reading at: https://dev.gnupg.org/T1752

Answer 2

User ruhri's solution did not work for us on our Debian stretch systems. At least, we had to add more socket "redirects". Here is what worked for us.

1. Create the .gnupg/S.gpg-agent file as described by ruhri:

   %Assuan%
   socket=/srv/scratch/joeuser/S.gpg-agent
   

2. Add these two lines to the end of .gnupg/gpg-agent.conf (create file if it does not already exist):

   extra-socket /srv/scratch/joeuser/S.gpg-agent.extra
   browser-socket /srv/scratch/joeuser/S.gpg-agent.browser
   

3. Create the file .gnupg/S.gpg-agent.ssh similar to the file .gnupg/S.gpg-agent:

   %Assuan%
   socket=/srv/scratch/joeuser/S.gpg-agent.ssh
   

This solution comes from this comment.